An echo cancellation method includes steps of (a) extracting phase-distortion estimates, (b) reconstructing an echo signal, (c) generating a clean signal, and (d) producing a primary signal. Step (a) includes extracting, from a first phase signal, a plurality of phase-distortion estimates, the first phase signal having been estimated from an echo-corrupted signal received at a first coherent transceiver of a coherent optical network. Step (b) includes reconstructing an echo signal from the plurality of phase-distortion estimates and a transmitted signal transmitted by the first coherent transceiver. Step (c) includes generating a clean signal as a difference between the reconstructed echo signal and the first phase signal. Step (d) includes producing a primary signal by mapping each of a plurality of clean-phase estimates of the clean signal to one of a plurality of constellation symbols associated with a modulation scheme of the primary signal.
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2. The echo cancellation system of claim 1, further comprising at least one of (i) an application-specific integration circuit and (ii) a field-programmable gate array configured to implement the functionality of at least one of the phase-distortion estimator, the adaptive filter, the subtractor circuit, and the decision decoder.
4. The echo cancellation system of claim 1, further comprising a synchronizer circuit configured to synchronize the transmitted signal to the phase-distortion signal to yield the synchronized transmitted signal.
7. The echo cancellation system of claim 6, further comprising at least one of (i) an application-specific integration circuit and (ii) a field-programmable gate array configured to implement the functionality of at least one of the decision decoder, the phase-distortion estimator, the adaptive filter, the subtractor circuit, and the additional decision decoder.
10. The echo cancellation system of claim 9, further comprising at least one of (i) an application-specific integration circuit and (ii) a field-programmable gate array configured to implement the functionality of at least one of the decision decoder, the subtractor circuit, the phase-distortion estimator, the adaptive filter, the additional subtractor circuit, and the additional decision decoder.
13. The echo cancellation system of claim 12, the modulus equalizer including an adaptive filter.
14. The echo cancellation system of claim 13 the adaptive filter being a two-by-two tap butterfly adaptive filter.
15. The echo cancellation system of claim 12, further comprising at least one of (i) an application-specific integration circuit and (ii) a field-programmable gate array configured to implement the functionality of at least one of the modulus equalizer, the phase-distortion estimator, the adaptive filter, the subtractor circuit, and the decision decoder.
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March 22, 2021
August 23, 2022
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